The production of polymers such as polyethylene requires a catalyst system that enables polymerization of monomers (e.g., ethylene). The amount of each catalyst system component in a polymerization reactor is an important process parameter which can impact the outcome of the polymerization reaction (e.g., polymerization yield, and properties of the resulting polymer). When the catalyst system contains solid components, it can be difficult to accurately measure the amount of solid components fed to a polymerization reactor, in part due to the solid components being introduced to the reactor as a heterogeneous mixture (e.g., a solid component in a fluid mixture, such as a slurry). In some instances, the contents of the polymerization reactor can be sampled and analyzed to calculate how much catalyst system component(s) was present in the reactor, but such analysis does not generally provide for adjusting the amounts of catalyst system components in the reactor in real-time or near real-time. Thus, there is an ongoing need for developing processes for real-time monitoring of the amount of catalyst system components in a polymerization reactor (e.g., in a reactor feed stream).